Product Code: ICAL06_M405

KrF Excimer Laser Processing of Human Dental Hard Tissues
Authors:
Rui Vilar, IST; Lisboa Portugal
Sivakumar Manickam, IST; Lisboa Portugal
Vitor Oliveira, IST; Lisboa Portugal
Presented at ICALEO 2006

Laser surface treatment is a promising technique for applications in dentistry such as the prevention of caries, the reduction of dental hypersensitivity and the improvement of bond strength between dentin and restorative materials. In this study, the morphological and chemical changes of human enamel and dentin surfaces after KrF excimer laser irradiation was characterized by scanning electron microscopy, X-ray diffraction and X-ray photoelectron spectroscopy. For radiation fluences near the ablation threshold of enamel (1.2 J/cm²), laser processing originates a relatively porous surface due to preferential removal of the organic matter around the enamel prism sheath, while for dentin at fluences near ablation threshold (0.5 J/cm²), cone like topography is developed due to the differential ablation mechanism between intertubular and peritubular dentin. In addition, the observed topography in dentin depends on the inclination of tubules with respect to laser beam direction. Increasing the fluence leads to a relatively flat surface with clear evidence of surface melting in enamel. For dentin the treated surface is covered with a layer of re-solidified material at high fluence values. For the fluence range used (0.5 to 10 J/cm2), both enamel and dentin showed reduction of organic content without significant changes in the mineral part. Analysis of the properties and electronic structure of dentin and enamel constituents are used in conjunction with modelling to identify the main ablation mechanisms involved and to provide guidelines for the selection of parameters for practical applications.